Alternative transmission and encoding techniques have been considered in order to support a larger number of devices and communications for future wireless communications systems. Different data encoding techniques, such as sparse code multiple access (SCMA), have been proposed as improvements over existing code division multiple access (CDMA) schemes. In SCMA systems, binary data streams are encoded directly to multi-dimensional codewords to spread data over multiple subcarriers or resource elements. Because of the sparse encoding of data, decoding techniques such as a message passing algorithm (MPA) may be used. The complexity of the MPA increases, however, as the number of users and communications increase.